using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cms
{
	public class EncryptedContentInfo
		: Asn1Encodable
	{
		private DerObjectIdentifier	contentType;
		private AlgorithmIdentifier	contentEncryptionAlgorithm;
		private Asn1OctetString		encryptedContent;

		public EncryptedContentInfo(
			DerObjectIdentifier	contentType,
			AlgorithmIdentifier	contentEncryptionAlgorithm,
			Asn1OctetString		encryptedContent)
		{
			this.contentType = contentType;
			this.contentEncryptionAlgorithm = contentEncryptionAlgorithm;
			this.encryptedContent = encryptedContent;
		}

		public EncryptedContentInfo(
			Asn1Sequence seq)
		{
			contentType = (DerObjectIdentifier) seq[0];
			contentEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(seq[1]);

			if (seq.Count > 2)
			{
				encryptedContent = Asn1OctetString.GetInstance(
					(Asn1TaggedObject) seq[2], false);
			}
		}

		/**
		 * return an EncryptedContentInfo object from the given object.
		 *
		 * @param obj the object we want converted.
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static EncryptedContentInfo GetInstance(
			object obj)
		{
			if (obj == null || obj is EncryptedContentInfo)
				return (EncryptedContentInfo)obj;

			if (obj is Asn1Sequence)
				return new EncryptedContentInfo((Asn1Sequence)obj);

			throw new ArgumentException("Invalid EncryptedContentInfo: " + obj.GetType().Name);
		}

		public DerObjectIdentifier ContentType
		{
			get { return contentType; }
		}

		public AlgorithmIdentifier ContentEncryptionAlgorithm
		{
			get { return contentEncryptionAlgorithm; }
		}

		public Asn1OctetString EncryptedContent
		{
			get { return encryptedContent; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * EncryptedContentInfo ::= Sequence {
		 *     contentType ContentType,
		 *     contentEncryptionAlgorithm ContentEncryptionAlgorithmIdentifier,
		 *     encryptedContent [0] IMPLICIT EncryptedContent OPTIONAL
		 * }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector(
				contentType, contentEncryptionAlgorithm);

			if (encryptedContent != null)
			{
				v.Add(new BerTaggedObject(false, 0, encryptedContent));
			}

			return new BerSequence(v);
		}
	}
}
